Suspended platform rigs for ship hulls and the like

ABSTRACT

A method of suspending a plurality of working platforms adjacent a surface of a structure and a rig of platforms which can be readily attached and dismounted from the structure by the said method. The rig comprises two pairs of arms, which can comprise brackets bolted directly onto the structure, with the two arms of each pair spaced vertically one above the other and the two pairs of arms spaced laterally along the surface. Two pairs of flexible elements are attached between the arms of each pair with an element extending between the two arms of each pair closely adjacent the structure and an element extending between the two arms of each pair at a position spaced outwardly of the structure from the other element. Working platforms or platform frames are then attached to the flexible elements by link means with each corner of a platform linked thereby to one of the flexible elements. The assembled rig is mounted on the structure by attaching the four arms to the structure, requiring only four fixing points and is readily dismounted therefrom.

United States Patent 1191 Reed 1451 Apr. 30, 1974 [5 1 SUSPENDED PLATFORM RIGS FOR SHIP 3,603,428 9/1971 Hanses 182/82 HULLS AND THE LIKE [76] Inventor: Ronald Reed, 6 St. Cuthburts Tern, Primary Examiner ke inaldo Machado Hexham, England Attorney, Agent, or F1rm-Kenyon & Kenyon Re1l1y Carr & Chapin 1 [22] Filed: May 15, 1972 [21] Appl. No.: 253,228 [57 S A Related US. Application Data- Continuation-in-part of Ser. No. 99,829, Dec. 21, 1970, abandoned.

Foreign Application Priority Data Dec. 22, 1969 Great Britain 62257/69 US. Cl. 182/82, 182/130 A method of suspending a plurality of working platforms adjacent a surface of a structure and a rig of platforms which can be readily attached and dismounted from the structure by the said method. The rig comprises two pairs of arms, which can comprise brackets bolted directly onto the structure, with the two arms of each pair spaced vertically one above the other and the two pairs of arms spaced laterally along the surface. Two pairs of flexible elements are attached between the arms of each pair with an element extending between the two arms of each pair closely adjacent the structure and an element extending between the two arms of each pair at a position spaced outwardly of the structure from the other element. Working platforms or platform frames are then attached to the flexible elements by link means with each comer of a platform linked thereby to one of the flexible elements. The assembled rig is mounted on the structure by attaching the four arms to the structure, requiring only four fixing points and is readily dismounted therefrom.

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I I as 7 53a iATENTED PR 30 1914 3807529 sum s m 8 .QATENTEDAPRBO 1914 *SHEET 7 BF 8 SUSPENDED PLATFORM RIGS FOR SHIP HULLS AND THE LIKE This application is a continuation-in-part of US. Patent Application Ser. No. 99,829, filed Dec. 21, 1970, now abandoned.

The present invention is concerned with a method of suspending one or more platforms adjacent the surface of an upstanding structure, such as a ships hull and also with a suspended platform rig for attachment to a face of a structure such as a plate of a ship's hull.

When a large upstanding structure such as a ships hull, which is curved about two axes, or a gasometer which is curved about a vertical axis, is in the process of construction it is necessary to provide a series of horizontal platforms along the face of the structure at several levels for workmen carrying out operations on the component plates of the structure, such as rivetting or welding. These horizontal platforms can be supported in one of several ways.

A plurality of outwardly projecting brackets can be welded or rivetted to the structure and scaffold boards placed across the brackets. This method has the disadvantages that the boards have to overlap to accommodate the curvature of the structure in a horizontal plane, which is wasteful of material and can be dangerous, and the brackets which support the boards have to be removed when the structure is finished and the outer surface of the structure planished. This is a very time consuming operation and a particular disadvantage in the ship building industry since this operation must be carried out before a ships hull is launched.

Another method employed hitherto, is to build scaffolding alongside the structure to support scaffold boards or other working platforms. However, in the ship building industry, since a ship's hull has a multiple curvature, the scaffolding has to be stepped in a vertical sense as well as having to accommodate a curve in the horizontal plane. The scaffolding structure thus has to fill the entire volume beneath the outermost periphery of the hull, which adds considerably to the expense.

A further method employed hitherto is to sling a suspended platform on two pairs of ropes from the 'top of the structure. This method is normally employed for repair work and has the disadvantages that the platform is not attached to the side of the structure and consequently is inapplicable if the surface of the structure curves inwardly. In addition, the platform itself tends to be unstable and liable to move which is dangerous.

With these problems in mind it is an object of the present invention to provide a method of suspending one or more platforms adjacent the surface of an upstanding structure, such as a ships hull, which is quick and easy to erect and dismantle and which provides a secure and safe platform for workmen. Additionally, it is an object of the present invention to provide a suspended platform rig including a plurality of platforms, which can be attached to a structure having either a flat surface or a multiple curved surface and dismantled therefrom as a single unit.

It will be understood that, while the invention is described in relation to the rigging ofa ships hull it is not limited to this application and can be advantageously employed to rig platforms adjacent any upstanding structure.

According to the present invention there is provided a method of suspending one or more platforms adja-.

cent the surface of an upstanding structure comprising the following steps (not necessarily carried out in the following sequence) of:

a. attaching two first arms to the structure one above the other so that they project outwardly relative to the surface,

b. attaching two second arms to the structure one above the other so that they project outwardly relative to the surface at a position spaced laterally along the surface from the first arms,

c. attaching a first pair of elongate flexible elements between the first arms with one of the first elements positioned adjacent the surface and the other first element spaced outwardly of the surface from the said one first element,

d. attaching a second pair of elongate flexible elements between the second arms with one of the second elements positioned adjacent the surface and the other second element spaced outwardly of the surface from the said one second element and According to a further aspect of the invention there is also provided a suspended platform rig for attachment to a face of a structure comprising a first pair of arms and a second pair of similar arms, each arm being adapted for attachment to the said structure so as to project outwardly with respect to a surface of the said structure, a first pair of continuous, unbroken main chains attached in spaced relationship between the first pair of arms so as to extend generally in parallel therebetween, a second pair of continuous unbroken main chains attached in spaced relationship between the second pair of arms so as to extend generally in parallel therebetween and at least one rectangular platform means adapted to support a substantially flat load bearing surface, the said platform means extending between the two pairs of main chains and being attached to each of the main chains by link means adapted to allow for limited movement of the platform relative to the respective main chain. I

As stated above the flexible elements preferably comprise steel chains and it is also an advantage to provide a platform which is telescopically extensible to accommodate variations in the lateral spacing of the pairs of flexible elements and variations in the curvature of the surface in a horizontal plane. lt is also a feature of the invention to attach the platform to the main chains by secondary chains which thus form flexible couplings.

In certain applications it is advantageous to brace the flexible elements from the surface of the structure so as to restrain lateral movement of the flexible elements. This is preferably achieved by bracing members in the form of telescopic transoms which are attached to the elements or to the platforms and which brace the chains from the surface of the structure.

FIG. 3 is a side elevation, on an enlarged scale, of a bracket forming a part of the rig shown in FIGS. 1 and FIG. 4 is a rear elevation of the bracket shown in FIG. 3,

FIG. 5 is a side elevation, partly in section of a fixture for clamping the bracket shown in FIGS. 3 and 4 to the ships plate shown bolted to the ships plate,

FIG. 6 is an illustration, in diagrammatic form, of the manner in which a platform forming a part of the rig of FIGS. 1 and 2 is attached to the flexible supporting elements of the rig,

FIG. 7 is an elevation of a part of a telescopic platform forming a part of the rig of FIGS. land 2,

FIG. 8 is a plan view of the platform shown in FIG. 7,

FIG. 9 is an elevation, on an enlarged scale, showing a detail of the manner in which the platform of FIGS. 7 and 8 is attached to the flexible supporting elements of the rig,

FIG. 10 is a plan vview of the detail shown in FIG. 9,

FIG. 11 is a side elevation of a chain clamp forming a part of the rig of FIGS. 1 and 2,

FIG. 12 is a side elevation of the chain clamp shown in FIG. 11, and

FIG. 13 is a side elevation, similar to FIG. 2, showing a detail of the rig attached to a curved structure.

In FIGS. 1 and 2 a rig of suspended platforms, which is indicated generally at 10 is shown attached to the outer surface of a plate 11, which forms a part of a ships hull. As can be seen from FIG. 2, the ships hull, of which the plate 11 forms a component part, is inclined upwardly and outwardly to the vertical and may also be curved about a vertical axis as shown in FIG. 13 so that the platforms have to follow the curvature of the hull in a horizontal plane and be stepped in a vertical sense.

The rig 10 comprises a first pair of brackets 12 and 13 which are attached to the plate 11 and spaced vertically one above the other, a second pair of brackets 14, which are spaced laterally along the plate 11 from the brackets l2, 13, a first pair of elongate flexible elements in the form of steelchains 16 and 17 which are attached in spaced relationship between the brackets 12 and 13, a second pair of elongate flexible elements in the form of chains 18 and 19 which are attached in spaced relationship and generally in parallel between the brackets 14 and 15 and three telescopically extensi- Y ble platform means 20, 21 and 22 each of which is clamped at one end to the chains 16 and 17 and at the other end to the chains 18 and 19 so as to extend generally horizontally. Each platform means 20, 21 and 22 may comprise a unitary body or a frame adapted to support a substantially flat load bearing surface, as dey bracket 12 comprises a horizontal, main arm 23 and downwardly depending secondary arms 24 and 25 which are welded to the main arm 23 to form a triangular frame-The main arm 23 extends rearwardly of the arm 24 and is attached by a bolt 26 to a fixture 27 comprising two spaced lugs 27a which are welded to a bearing plate 28 and between which the end of the arm 24 is located and bolted. The bearing plate 28 is itself attached to the ships plate, as shown in FIG. 5, by a main bolt 29 which extends through the bearing plate 28, and into a stepped bearing block 30 where it is securely threadedly engaged. As can be seen from FIG. 5, the block 30 includes a bush portion which projects into an aperture, preformed in the plate 11. Upper and lower links 31 and 31a respectively are bolted to the main arm 23 and to the lower arms 24, 25'respectively, as can be seen from FIG. 3, and are each provided with feet which rest against the plate 1 1. Two further lateral, supporting struts 32, 32a are also bolted to the arm 23 and have feet which rest on the plate 11. The main horizontally extending arm 23 of the bracket 12 is thus supported and stabilised at four points and attached directly to the ships plate 11 by the fixture 27.

The four brackets 12, 13, '14 and 15 are attached to the plate 1 1 in the manner described above with reference to the bracket 12 so that the upper brackets 12 and 14 are spaced vertically from the lower brackets 13 and 15 by a distance which can range from l5 feet to feet and with the first pair of brackets l2, l3 spaced laterally from the second pair of brackets l4, 15 by a distance which can range from 6 feet to 20 feet.

The upper brackets 12 and 14 can if necessary be replaced by arms which project outwardly relative to the surface of the hull from the top of the ships hull and which are attached, inwardly of the hull to the ships deck, for instance with the aid of a mounting bracket welded to the deck.

The steel chains 16, 17, 18 and 19 are then attached between the brackets with the inner chains 16, 18 attached to the arms 23 of the brackets so as to extend generally parallel to and closely adjacent the surface of the plate 11, i.e., approximately 12 inches from the surface of the plate 11. The outer chains 17, 19 are attached to the free ends of the arms 23 so as to be spaced outwardly of the plate 11 from the inner chains 16, 18 by a distance of approximately 27 inches. The upper ends of the steel chains 16, 17, 18 and 19 are shackled to the upper brackets in a conventional manner to providea secure fixing and the lower ends of the steel chains 16 to 19 are drawn inwardly and shackled to the lower brackets so as to extend generally in parallel with the ships hull.

When the chains are in position, the platforms 20,21, 22 are attached to the chains by a plurality of flexible couplings in a manner illustrated diagrammatically in FIG. 6. Since the platforms 20, 21, 22 and their manner of attachment to the chains is identical only the platform 20 and its manner of attachment will be described in detail with reference to Figures to 12.

As can be seen from FIG. 6, the platform 20 is attached at each of its four corners to one of the main steel chains 16 to 19 by link means in the form of a secondary steel coupling chain 33 and two similar chain clamps 34 so that it is suspended from the main chains 16 to 19 generally horizontally but so that it is free to move within limits imposed by the tension in the main chains and the secondary coupling chains.

The platform comprises a main section 36, which is in the form of an inverted channel-section sleeve and two end sections, 37 and 38, only one of which is shown in FIGS. 7 and 8 and which are telescopically slidable into the main section 36. The main section 36 of the platform 20 comprises a rolled section steel frame 39 carrying a load bearing board 40 which forms the upper face of the platform 20. The frame 39 is formed along its lower longitudinal edges with U-shaped runners (not shown) and each outer section 37 and 38, which also comprises a rolled section steel frame 42 and load bearing board 43, is slidable on the runners of the main section. The transverse ends of the outer sections 37 and 38 are formed by channel section steel struts 44 and each corner of the two outer sections 37 and 38 is provided with four tubular bushes 45 which extend through the end sections 37 and 38 normally to the major faces of the platform and which project outwardly from both sides of the platform. The purpose of the tubular bushes 45 will be explained below.

The main section 36 of the platform 20 is preferably 12 feet in length and the two end sections 37 and 38 are 6 feet in length so that the platform 20 is extensible from a length of approximately 12 feet to approximately 18 feet in length. Stops are provided within the main section 36 to ensure that the end sections 37 and 38 cannot be withdrawn accidentally from the main section further than half their length. It will be appreciated that the length of the main section and the outer sections of the platform can be varied to give different range of overall platform length to suit a specific requirement.

Welded to the underside of each end of the main section 36 of the platform are three spaced guide brackets 70 and 71 respectively, which receive transoms 72 and 73 respectively. The transoms are slidably engaged through the guide brackets and can be locked in any required position relative to the platform. The inner end of each transom 72 and 73 is provided with means for releasably and pivotally attaching the transom to a mounting bracket 74 and 75 respectively which rests against the plate 11. As can be seen best from FIG. 13, the transoms 72 and 73 act as bracing means to brace the platform 20, and thereby the two pairs of chains l6, l7 and 18,19, from the plate 11 and restrain lateral movement of the chains in a direction parallel with the surface of the plate. The transoms can comprise telescopic tubes or bars of square section and they can be connected directly to the main chains, instead of to the platform 20. It is preferred to provide a pair of transoms for each platform, but in certain applications more or less pairs may be used.

The platform 20 is attached to the main chains 16 to 19 by first passing one of the secondary chains 33 through one of the tubular bushes 45, as shown in FIG. 9 and 10. Similar load plates 46 and 47 each of which is formed with a slot 48 extending into one edge, are then located across the upper and lower ends of each bush 45 with the links of the chain 33 located within the slots 48 and finally two similar fillets 49 are bolted to the load plates 46 and 47 across the slots 48 to prevent the links of the chain from sliding out of the slots 48. The weight of the platform is then taken on the bottom plates 47.

The ends of the secondary chains 33 are then clamped to the main chains 16 to 19 with the aid of chain clamps 34, which are permanently attached to each clamped, at both ends, to their respective main the ends of the chains 33 and one of which is shown in detail in FIGS. 11 and 12.

The clamp 34 comprises a shallow channel section member 50 having opposed side walls 51,52 joined by a flat web 53, and a clamping plate 54 which fits within side walls of the member 50. The plate 54 has two upstanding lugs 55, 56 which are welded to the plate and the lugs -55, 56 are formed with aligned apertures 57, 58. The end link of the coupling chain 33 is located between the lugs 55, 56 and attached thereto by a bolt 59 which passes through the apertures 57, 58 and through the end link.

Both the web 53 of the member 50 and the clamping plate 54 are formed with similar aligned slots 60 and 61 respectively and the plate 54 is attached to the web 53 by two bolts 62, 62a. In order to strengthen the plate 54 its edge portions 63, 63a are extended and curved upwardly.

In order to attach the clamp 34 to the main chain 16, the main chain is positioned through the channel shaped member 50 with one half of a link 16a located through the slot 60. The plate 54 is then placed between the walls 51, 52 with the other half of the link 16a projecting through the slot 61 in the plate and the bolts 62, 62a are tightened to clamp the link 16a between the web 53 of the member 50 and the plate 54.

When the four secondary-coupling chains 33 are chains the platform 20 is securely attached to the main chains and is braced from the surface of the ships hull by the transoms 72 and 73. When the rig is positioned on the hull, the extent to which the main chains are braced from the hull can be adjusted by adjustment of the position of each platform 20 on the associated transoms 72 and 73, which alters the tension in the main chains. Additionally, the clamps 34 can be readily removed and repositioned on a different link of the main chains and the load bearing plates 46 and 47 can also be readily repositioned on the secondary chains 33. The tension in the main chains and the position and orientation of the platform on the chains can thus be quickly and easily adjusted.

As can be seen from FIGS. 1 and 2 a safety bar 64 is provided on each platform. The safety bar is telescopically adjustable for adjustment to the length of the platform and is attached to the platform by spigots, not shown, which locate in the bushes 45 provided at each corner of the platform. A steel ladder 65 can also be provided on each platform, preferably hinged to the platform so that it can be swung upwardly from the position shown in FIG. 1 into a position adjacent the lower face of the platform 20 where it is held by a clip or strap.

Since the platforms 20, 21, 22 are telescopically extensible the lateral spacing between the main chains can be varied within wide limits and any gap between adjacent platforms which would normally occur when the platforms are on a sharply curved surface is accommodated by extending the end sections. It is also envisaged that a quadrant shaped connecting member (not shown) be provided to link adjacent platforms, when these are inclined to one another, the quadrant being attached to the adjacent ends of the two platforms by spigots which locate in the bushes 45.

lt will be understood that any number of platforms can be provided on the main chains but normally platforms would be provided spaced vertically six feet from one another.

Although steel chains are the preferred material for the flexible elongate elements which carry the platforms, other flexible elements can be used, for instance steel rope or wire provided with a plurality of connection points, such as eyelets, for coupling the platforms to the rope or wire. Alternatively, the elongate elements can comprise a plurality of rigid members which are jointed together so that the element as a whole is flexible although the component parts thereof are individually rigid.

If the rig 10 is used on a vertical face then the main chains 16, 17, 18 and 19 can be passed directely through the bushes 45 on the platforms and the platforms then supported by the plates 46 and 47 which are clamped directly onto the main chains instead of the secondary chains. The secondary chains and the chain clamps are thus eliminated and the platforms are attached directly to the main chains.

The main'chain s themselves can also be attached to the brackets l2, 13, 14 and by shackling the chains to the upper brackets 12 and I4 and by passing the lower ends of the chains through bushes provided on the lower brackets 13 and 15 and securing the lower ends ofthe chains beneath the brackets 13 and 15 by means of plates similar to the plates 46 and 47.

When the suspended platform rig 10 is attached, as described above to a steel plate forming a part of a ships hull it is preferable to attach the rig 10 to the plate before the plate is erected and welded into the hull structure, however this is not essential and the rig 10 can be attached directly to the ships hull.

If the rig 10 is attached to a plate of a ships hull having a sharp curvature it is often necessary to position the two pairs of chains 16, 17 and 18, 19 at a slight angle to one another so that thelength of the platforms in the one rig will vary. This variation in length is readily achieved by the use of the telescopic platforms.

Since the platforms should always be arranged as closely to the horizontal as possible the main chains, when attached to a curved surface will not extend normally to the platforms. if the platforms were clamped directly and rigidly on to the main chains this would distort the main chains and impose an additional strain on the main chains which in certain operating conditions may not be acceptable. The flexible coupling incorporating the secondary steel chain 33 enables the platform to be attached to the main chains securelybut without any distortion of the main chains regardless of their orientation relative to the plane in which the platform is positioned.

When the hull is completed the rig 10 is removed by unbolting the four brackets 12, 13, 14 and 1S and removing the entire rig as a single unit. The assembled unitary rig 10 can then be reused by attaching it as a unit to a new plate 11 on the factory floor or directly to a shipshull, the only operation that has to be performed'on the new plate being the drilling of four holes in the plate to take the four blocks 30. It will of course be understood that a plurality of rigs 10 will be required to rig a complete ships hull but the work involved in dismantling the rigs 10 from the hull and filling the four holes left in the hull by each rig is relatively small. When the rig is removed the four holes left on the plate are plugged and can readily be drilled out again if it is necessary to remount a rig l0 subsequently, for instance for repair work on the ships hull.

It will also be appreciated that each of the brackets 12, 13, 14 and 15 can readily be bolted either to the inside face or the outside face of the plate 1 1 with the aid of the fixture 27 and stepped block 30. Thus the entire rig can be applied to the inside face of a ships hull if this is required using only the same four preformed apertures in the plate 11 which receive the stepped blocks 30.

While the rig 10 has been described herein applied to a ship's hull it can be used on any upstanding structure and is particularly suitable for use in the chemical engineering industry on gasometers and similar storage tanks.

Further minor modifications can be made to the above described embodiment without departing from the spirit and scope of the invention which is best described in the following claims.

What I claim is:

l. A method of suspending at least one platform adja cent the surface of an upstanding structure comprising the following steps (not necessarily carried out in the following sequence) of:

a. attaching two first arms to the structure one above the other so that they project outwardly relative to the surface,

b. attaching two second arms to the structure one above the other so that they project outwardly relative to the surface at a position spaced laterally along the surface from the first arms,

c. attaching a first pair of elongate flexible elements between the first arms with one of the first elements positioned adjacent the surface and the other first element spaced outwardly of the surface from the said one first element,

(1. attaching a second pair of elongate flexible ele ments between the second arms with one of the second elements positioned adjacent the surface and the other second element spaced outwardly of the surface from the said one second element and e. locating the opposite ends of a horizontally disposed platform adjacent to the first pair of elements and the second pair of elements respectively and attaching the said platform to each of the elements of the said first and second elements so as to suspend the platform on the said elements and adjacent the surface.

2. A method as claimed in claim 1, including the step of bracing the said elongate flexible elements from the said surface with the aid of bracing means.

3. A method as claimed in claim 1, including the step of bracing the platform from the said surface with the aid of bracing means.

4. A method as claimed in claim 1, wherein the said platform is attached to each of the-said elements by a secondary chain which passes through the platform and is clamped at each end to a said element.

5. A method as claimed in claim 4, wherein the elongate flexible elements are steel chains.

6. A method as claimed in claim 5, wherein the platform is telescopically extensible to accommodate variations in the lateral spacing between the two pairs of flexible elements.

7. A method as claimed in claim 1, wherein the platform is attached to a component part of the structure prior to erection of the said component to form a composite part of the upstanding structure.

8. A method as claimed in claim 1, wherein at least one of the said arms is bolted to the structure with the aid of a stepped block which projects into an aperture in the surface from the side of the structure opposite to the said surface.

9. A method as claimed in claim 8, wherein the ends of the platform are attached to the said elements by secondary chains each of which passes through the platform and is clamped at each end to a said element.

10. A suspended platform rig assembly for attachment to a face of a structure comprising a pair of upper and lower supports each capable of being attached to the face of the structure, four flexible elongate main elements capable of extending generally parallel with one another between said upper and said lower supports, and a plurality of platforms each secured to all four elements at four spaced positions defining a quadrilateral figure in the plane of said platform; each platform being secured to said elements at positions spaced apart along the length of said elements by at least six feet to act as working platforms for men working against the face of the structure.

11. An assembly as set forth in claim 10 in which each platform has a safety bar for assisting in preventing a man for falling from the platform.

12. An assembly as set forth in claim 10 including a ladder secured to at least one platform to extend between successive platforms for enabling a man to move from one platform to another.

13. An assembly as set forth in claim 10 including intermediate supports capable of being attached to the face of the structure for holding an intermediate part of the assembly close to an inwardly curved part of the structure.

14. A rig as claimed in claim 10 and including bracing means adapted to brace the said main elements from the said face of the structure and restrain lateral movement of the said main elements.

15. A rig as claimed in claim 14, wherein the said bracing means comprises a telescopic transom member associated with each said pair of main elements and adapted to brace the elements of the said pair from the said face of the structure.

16. A rig as claimed in claim 15, wherein the said transom members are releasably attached to a platform so as to brace the platform from the said face of the structure.

17. A rig as claimed in claim 10, wherein each said platform is secured to each main element by link means which comprises a secondary element attached to a main element and passing through said platform.

18. A rig as claimed in claim 10, wherein the platform is telescopically extensible.

19. A rig as claimed in claim 17, whereinthe platform is formed with an aperture extending through the platform normally to the major faces of the platform adjacent each corner of the platform and a secondary chain passes through each of the apertures in the platform.

20. A plate of a ships hull having a rig of suspended platforms as claimed in claim 10 attached thereto.

21. A suspended platform rig for attachment to a face of a structure comprising a first pair of arms and a second pair of similar arms, each arm being adapted for attachment to the said structure so as to project outwardly relative to a surface of the said structure, at least one of said arms being an arm of an L-shaped bracket attached to a plate which is bolted to a stepped block, said block being adapted for insertion through an aperture in the structure from the opposite side thereof to the said face thereof whereby, when erected, the structure adjacent the rim of the aperture is clamped between said stepped block and said plate, a first pair of continuous unbroken main chains attached in spaced relationship between the first pair of arms so as to extend generally in parallel therebetween, a second pair of continuous unbroken main chains attached in spaced relationship between the second pair of arms so as to extend generally in parallel therebetween and at least one rectangular platform means, the said platform means extending between the two pairs of main chains and being attached to each of the main chains by link means adapted to allow for limited pivotal movement of the platform relative to the respective main chain. 7

22. A suspended platform rig for attachment to a face of a structure comprising a first pair of arms and a second pair of similar arms, each arm being adapted for attachment to the said structure so as to project out wardly relative to a surface of the said structure, a first pair of continuous unbroken main chains attached in spaced relationship between the first pair of-arms so as to extend generally in parallel therebetween, a second pair of continuous unbroken main chains attached in spaced relationship between the second pair of arms so as to extend generally in parallel therebetween and at least one rectangular platform means, said platform means extending between the two pairs of main chains and being attached to each of the main chains by link means adapted to allow for limited pivotal movement of said platform means relative to the respective main chain, each said link means comprising a secondary chain attached to a main chain and passing through the said platform means, and said platform means being a platform formed with an aperture extending through said platform normally to the major faces of said platform adjacent each corner of said platform and a secondary chain passes through each of said apertures in said platform, each said secondary chain being attached to a main chain by means ofa chain clamp comprising a channel-shaped member having a web formed with a slot therein and a plate formed with a complementary slot therein, a link of said main chain being located partly through said slot in said web of said member and partly through said slot in said plate and said plate being bolted to said web to clamp said link therebetween.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO. 3,807,529 Dated Apr. 30, 1974 (Ser. No. 253,228) (Filed May 15, 1972) Inventor(s) Ronald Reed SUSPENDED PLATFORM RIGS FOR SHIP HULLS AND THE LIKE 7 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

001. t, line 22, correct spelling of "stabilized".

I Col. 5, line 56, change "Fig. to --Figs Col. 7, line 1 4, correct spelling of "directly".

In claim 19, line 61, change "chain" to --element--.

Signed and sealed this 1st day of October 1974,

(SEAL) Attest:

McCOY M. GIBSON JR. 7 .C. MARSHALL DANN Attesting Officer Commissioner of Patents :ORM Po'wso H0459) USCOMM-DC scan-ps9 ".5. GOVERNMENT PRINTING OFFICE Z I!" 0-'3-3l. 

1. A method of suspending at least one platform adjacent the surface of an upstanding structure comprising the following steps (not necessarily carried out in the following sequence) of: a. attaching two first arms to the structure one above the other so that they project outwardly relative to the surface, b. attaching two second arms to the structure one above the other so that they project outwardly relative to the surface at a position spaced laterally along the surface from the first arms, c. attaching a first pair of elongate flexible elements between the first arms with one of the first elements positioned adjacent the surface and the other first element spaced outwardly of the surface from the said one first element, d. attaching a second pair of elongate flexible elements between the second arms with one of the second elements positioned adjacent the surface and the other second element spaced outwardly of the surface from the said one second element and e. locating the opposite ends of a horizontally disposed platform adjacent to the first pair of elements and the second pair of elements respectively and attaching the said platform to each of the elements of the said first and second elements so as to suspend the platform on the said elements and adjacent the surface.
 2. A method as claimed in claim 1, including the step of bracing the said elongate flexible elements from the said suRface with the aid of bracing means.
 3. A method as claimed in claim 1, including the step of bracing the platform from the said surface with the aid of bracing means.
 4. A method as claimed in claim 1, wherein the said platform is attached to each of the said elements by a secondary chain which passes through the platform and is clamped at each end to a said element.
 5. A method as claimed in claim 4, wherein the elongate flexible elements are steel chains.
 6. A method as claimed in claim 5, wherein the platform is telescopically extensible to accommodate variations in the lateral spacing between the two pairs of flexible elements.
 7. A method as claimed in claim 1, wherein the platform is attached to a component part of the structure prior to erection of the said component to form a composite part of the upstanding structure.
 8. A method as claimed in claim 1, wherein at least one of the said arms is bolted to the structure with the aid of a stepped block which projects into an aperture in the surface from the side of the structure opposite to the said surface.
 9. A method as claimed in claim 8, wherein the ends of the platform are attached to the said elements by secondary chains each of which passes through the platform and is clamped at each end to a said element.
 10. A suspended platform rig assembly for attachment to a face of a structure comprising a pair of upper and lower supports each capable of being attached to the face of the structure, four flexible elongate main elements capable of extending generally parallel with one another between said upper and said lower supports, and a plurality of platforms each secured to all four elements at four spaced positions defining a quadrilateral figure in the plane of said platform; each platform being secured to said elements at positions spaced apart along the length of said elements by at least six feet to act as working platforms for men working against the face of the structure.
 11. An assembly as set forth in claim 10 in which each platform has a safety bar for assisting in preventing a man for falling from the platform.
 12. An assembly as set forth in claim 10 including a ladder secured to at least one platform to extend between successive platforms for enabling a man to move from one platform to another.
 13. An assembly as set forth in claim 10 including intermediate supports capable of being attached to the face of the structure for holding an intermediate part of the assembly close to an inwardly curved part of the structure.
 14. A rig as claimed in claim 10 and including bracing means adapted to brace the said main elements from the said face of the structure and restrain lateral movement of the said main elements.
 15. A rig as claimed in claim 14, wherein the said bracing means comprises a telescopic transom member associated with each said pair of main elements and adapted to brace the elements of the said pair from the said face of the structure.
 16. A rig as claimed in claim 15, wherein the said transom members are releasably attached to a platform so as to brace the platform from the said face of the structure.
 17. A rig as claimed in claim 10, wherein each said platform is secured to each main element by link means which comprises a secondary element attached to a main element and passing through said platform.
 18. A rig as claimed in claim 10, wherein the platform is telescopically extensible.
 19. A rig as claimed in claim 17, wherein the platform is formed with an aperture extending through the platform normally to the major faces of the platform adjacent each corner of the platform and a secondary chain passes through each of the apertures in the platform.
 20. A plate of a ship''s hull having a rig of suspended platforms as claimed in claim 10 attached thereto.
 21. A suspended platform rig for attachment to a face of a structure comprising a first pair of arms and a second pair of similar arms, each arm being adapted for attachment to the sAid structure so as to project outwardly relative to a surface of the said structure, at least one of said arms being an arm of an L-shaped bracket attached to a plate which is bolted to a stepped block, said block being adapted for insertion through an aperture in the structure from the opposite side thereof to the said face thereof whereby, when erected, the structure adjacent the rim of the aperture is clamped between said stepped block and said plate, a first pair of continuous unbroken main chains attached in spaced relationship between the first pair of arms so as to extend generally in parallel therebetween, a second pair of continuous unbroken main chains attached in spaced relationship between the second pair of arms so as to extend generally in parallel therebetween and at least one rectangular platform means, the said platform means extending between the two pairs of main chains and being attached to each of the main chains by link means adapted to allow for limited pivotal movement of the platform relative to the respective main chain.
 22. A suspended platform rig for attachment to a face of a structure comprising a first pair of arms and a second pair of similar arms, each arm being adapted for attachment to the said structure so as to project outwardly relative to a surface of the said structure, a first pair of continuous unbroken main chains attached in spaced relationship between the first pair of arms so as to extend generally in parallel therebetween, a second pair of continuous unbroken main chains attached in spaced relationship between the second pair of arms so as to extend generally in parallel therebetween and at least one rectangular platform means, said platform means extending between the two pairs of main chains and being attached to each of the main chains by link means adapted to allow for limited pivotal movement of said platform means relative to the respective main chain, each said link means comprising a secondary chain attached to a main chain and passing through the said platform means, and said platform means being a platform formed with an aperture extending through said platform normally to the major faces of said platform adjacent each corner of said platform and a secondary chain passes through each of said apertures in said platform, each said secondary chain being attached to a main chain by means of a chain clamp comprising a channel-shaped member having a web formed with a slot therein and a plate formed with a complementary slot therein, a link of said main chain being located partly through said slot in said web of said member and partly through said slot in said plate and said plate being bolted to said web to clamp said link therebetween. 